1. Field of the Invention
The present invention relates to the field of optical recording media, and more particularly, to a disc having information on the sizes of allocated spare areas and the remaining amounts thereof, in which an appropriate amount of a primary spare area is allocated upon initialization, and a supplementary spare area is allocated if the primary spare area is insufficient while being used after completion of initialization, a method of allocating the spare areas, and a method of managing the defects of the primary and supplementary spare areas.
2. Description of the Related Art
In recording media such as general discs, a spare area is allocated once upon initialization and no supplementary spare area is allocated during use of the disc. However, in order to increase the efficiency of using a disc, an appropriate amount of spare area is allocated according to the state of the disc upon initialization, and a supplementary spare area is allocated when the spare area allocated upon initialization is insufficient while the disc is being used.
According to a digital versatile disc random access memory (DVD-RAM) standard (DVD Specifications for Rewritable Disc, Part 1 PHYSICAL SPECIFICATIONS) version 1.0, each zone has one spare area, so that 24 spare areas are allocated upon initialization since a disc has 24 zones.
In the related art, as shown in FIG. 1, a flag representing the state of the spare area allocated to each zone within a defect management area (DMA) is constituted of only one bit, which represents whether or not a corresponding spare area can be used, i.e., whether it is occupied. Bits b0 to b63 represent 64 bits of information. Accordingly, a full spare area flag has 24 bits of information representing whether or not 24 spare areas are occupied. Groups Group0 to Group23 are groups corresponding to bits b0 to b23. Bits b24 to b63 shown as “Reserved”, i.e., unused spare areas. Also, this full spare area flag is stored in relative byte positions (RBP) 8 to 15 of a secondary defect list (SDL) of the DMA. When a bit representing a corresponding group is “1”, this represents that no spare area remains within the corresponding group, and when the bit is “0”, this represents that a spare area remains within the corresponding group.
Information on a spare area, which is constituted of only one bit as described above, represents only whether the spare area is occupied. On the other hand, in discs in which a supplementary spare area can be allocated after initialization, it is preferable that the supplementary spare area is allocated on a disc when the spare area has some room in a state of being almost occupied rather than when the spare area is completely occupied. However, a problem occurs in that the state in which the spare area is almost occupied cannot be represented by only the one bit.
Also, in the allocation of spare areas according to the existing DVD-RAM standard version 1.0, a predetermined amount of spare area is allocated to each zone upon initialization, the size of which is predetermined to be sufficient to process all defects that can be managed by a defect management method that is applied to a corresponding disc.
Here, in order to manage defects on a general recordable/rewritable disc, a slipping replacement method of skipping defects without providing logical sector numbers to the defects, is not used for defects generated upon initialization of the disc, which are called “primary defects.” It is prescribed in the existing DVD-RAM standard version 1.0 that the position of a defective sector replaced by slipping replacement must be recorded in a primary defect list (PDL) in a DMA on a disc. Also, linear replacement for replacing error correction code (ECC) blocks of an erroneous zone with normal blocks in a spare area, is used for defects generated during use of the disc, which are called “secondary defects.” It is prescribed in the existing DVD-RAM standard version 1.0 that the position of a defective block replaced by linear replacement must be recorded in an SDL in a DMA on a disc.
However, when an appropriate amount of spare area is allocated according to the state of a disc upon initialization, and a supplementary spare area is allocated as the state of the disc becomes bad during use of the disc (“bad” meaning that the more the disc is used, the more defects it has), a more effective spare area allocating method is required. It is prescribed in the existing standard that in a recording and/or reproducing apparatus of a disc, the size of a buffer for temporarily storing defect management information existing on a disc is 32 Kbytes. Accordingly, a restriction is generated in that the actual number of defects that can be managed becomes less than the number of defects that can be recorded in the DMA on the disc.
Here, the defect management information includes PDL and SDL, and the sum of the sizes of the PDL and SDL is about 60 Kbytes. Thus, in the DVD-RAM standard version 1.0, PDL ranges from sectors 1 to 15, and the remaining sectors are set to be used to process SDL entries, so that the number of PDL entries and SDL entries that can be processed is restricted in accordance with the size (32 Kbytes) of a buffer of a recording and/or reproducing apparatus.